portland independent media center  
images audio video
newswire article reposts global

education | environment

Modern agriculture and biodiversity: uneasy neighbours

If you think biodiversity is going to get equal weight in any policy decision, then you should really go visit agriculture land and look at the war being waged against biodiversity.
Modern agriculture and biodiversity: uneasy neighbours

Barbara Gemmill and Ana Milena Varela

1 February 2004 | EN

 link to www.scidev.net

Introduction

Humanity has been farming for at least 10,000 years. For most of that time, agriculture has been small-scale, labour-intensive and relatively low-tech. The last half-century, however, has witnessed a rapid revolution in the technology of agricultural production, particularly in the developed world, that has allowed the widespread adoption of industrial-scale farming techniques.

By contrast, the agricultural landscape in many of the poorest countries continues to be dominated by smallholder farmers growing crops either for their own subsistence, or for markets over which they have limited influence. Governments, particularly in developing countries, are no longer investing heavily in agriculture. But they remain keen, on the one hand, to ensure that their countries produce enough food for their growing populations, and on the other, to exploit any opportunities that exist in the export market.

Developing countries that try to meet these two objectives find themselves in a dilemma. Highly productive agriculture is undoubtedly good for a country's social and economic stability. And greater agricultural productivity should, in theory, enhance food security and raise standards of living in farming communities. But there is growing evidence, backed by a substantial body of research, that modern agricultural techniques - in both rich and poor countries - are helping to undermine the natural resource base of the economies that depend upon it. This includes contributing significantly to the loss of biodiversity.

The aim of this policy brief is to outline the challenges, and some of the choices, that face policymakers in the developing world who want to increase the agricultural productivity of their country, yet also safeguard biodiversity. In this way they might prevent the sacrifice of their populations' long-term interests in favour of short-term social or economic gains.

The interdependence of nature

By its very nature, modern agriculture to a large extent involves managing land in ways that conflict with the conservation of biodiversity and the healthy functioning of ecosystems. For example, industrial agriculture often requires fields to be levelled and hedgerows removed. Similarly, single crops are planted over large areas, and 'rest periods' - which allow natural vegetation to re-grow - are eliminated. All these factors, in addition to the heavy use of pesticides and chemical fertilisers, tend to lead to major losses of biodiversity, particularly where land is managed in a way that is aimed primarily at maximising agricultural productivity.

Yet healthy ecosystems and flourishing biodiversity are critical for the long-term sustainability of agriculture. There are several reasons for this. First, the crops and livestock upon which modern agriculture depend are themselves a valuable part of the Earth's genetic resources.

Furthermore, agriculture depends on a number of natural processes, sometimes described as 'environmental services', such as water supply, the cycling of nutrients in soils, pollination, natural means of pest control and carbon sequestration. These services are provided by many types of plants and animals, ranging from trees to soil bacteria and native bees.

If these plants and animals - many whose role has yet to be identified - are lost, the environmental services they provide may well disappear with them. When a single species is lost, its associated environmental service may well be replaced by other species. But with serious losses, the optimal providers of services will almost certainly be affected.

One consequence is that the productivity of agricultural land begins to suffer, as has already been observed. Human activities, for example, have significantly disturbed the water, carbon and nitrogen cycles, which has had consequences as far-reaching as global climate change. And in many parts of the world, modern farming methods have seriously degraded the soil, requiring the massive application of fertilisers in order to avoid a steady decline in levels of agricultural productivity.

The impact of industrial agriculture on biodiversity

Knowledge of the relationship between agriculture and biodiversity has greatly improved with data from recent studies, including those by the Consultative Group on International Agricultural Research and the UN Food and Agriculture Organisation (FAO). Satellite data, for example, shows us that 28 per cent of the Earth's surface is used for agriculture and livestock rearing. We also know that 41 per cent of the world's farmland is managed fairly intensively, using heavy machinery and agricultural chemicals. Most of the land under intensive agricultural management is in Europe and parts of North America, although there is also a substantial amount of land farmed in this way in India and Southeast Asia.

Furthermore, almost half the world's temperate and dry tropical/subtropical forests has been converted to agriculture since the 1700s. Indeed, 25 per cent of the change has happened in the past 50 years alone.

The area used to grow most of the staple crops critical to food security has remained relatively consistent - at around 1.3 billion hectares - for the past 25 years. Food production, on the other hand, has increased substantially, thanks largely to agricultural research that has led to the development of high-yielding crops for the developing world (a process generally termed the 'Green Revolution'). Indeed, according to some estimates, a further 3 billion hectares of non-agricultural land would have been converted to farming had it not been for Green Revolution productivity gains. [1,2]

But such trends cannot continue unmodified. Modern agricultural practices, many developed through the Green Revolution, are seriously reducing the productivity of agricultural land in both developed and developing countries. Soil degradation from agricultural practices is already reducing yields on about 16 per cent of agricultural land, especially cropland in Central America and both cropland and pastures in Africa. [1] Additionally, the widespread use of pesticides has led to the emergence of many pesticide-resistant pests and pathogens.

More water for farms, less for nature

Another damaging factor has been irrigation, on which much agriculture relies. The heavy use of water was an important contributor to the productivity gains of the Green Revolution. Indeed, in global terms, agriculture now accounts for the largest proportion of withdrawals from both surface and groundwater sources, using more than industry, and more than households. And even though agriculture's overall share of the world water supply is likely to fall by 2025, some researchers predict that agriculture in developing countries will need 50 per cent more water than it does today.

Irrigation has left soils in many countries waterlogged and containing high levels of salt. It has also depleted reservoirs and groundwater sources. In the past century alone, over 50 per cent of the world's wetlands have been lost because of the demands of agriculture. And of the more than 3500 species currently under threat worldwide, 25 per cent are fish and amphibians.

In the great tropical rivers of Asia, Africa and Latin America, for example, large numbers of animal and plant species have adapted to regular flooding patterns. These species are now threatened from the construction of dams - many of which are being built to provide irrigation water for agriculture. [3] Such dams disrupt traditional flooding processes and threaten riverine biodiversity.

The potential conflict between the use of water for human purposes (particularly agriculture), and the need for water to sustain biodiversity, are well illustrated by the Pangani River of northern Tanzania. This river runs through some of the most biodiverse areas in the world, including the rich flora and fauna of the Eastern Arc Mountains (one of the world's 25 biodiversity 'hotspots') and the various estuaries and mangrove swamps where the river meets the sea.

The Pangani River and its catchment area provide water both to meet human needs and to sustain biodiversity in the area. Water extraction for irrigation, for example, has already severely reduced the flow of the river and its tributaries. One recent study showed that the amount of water extracted for human use is becoming dangerously close to the average amount of water flowing in the river. And the situation is likely to get worse. Water supplies in the Pangani Basin are already falling annually by about 6 per cent.

Admittedly, some of the additional water could be provided from more efficient use of water in agriculture. Revisiting the example of the Pangani basin, 85 per cent of water that is intended for human use is lost through leaks and other holes in the distribution system before it reaches users. Better management of natural ecosystems upstream from important agricultural lands - such as Mount Kilimanjaro and Mount Meru, upstream from the Pangani River - may be one of the best ways of securing regular water supplies for these competing uses.

The picture is not entirely negative. For example, efficient water use systems have been successfully applied in parts of the Middle East, where water stress and shared water systems are common. [4] Nevertheless, current trends are sufficiently worrying to suggest that purely technological solutions are unlikely, on their own, to combat all the problems that agriculture's demand for water is currently imposing on the world's biodiversity.

Learning to live together

What all this means is that modern agriculture has to change to become more biodiversity-friendly. Attempts are already made to achieve this. One approach is for farmers to leave areas of land untouched. For example, neighbouring farmers might be encouraged to protect adjacent areas of their farms, so that 'wildlife corridors' that connect natural habitats are maintained. Or farmers might allow uncultivated areas to exist around, and within, cultivated ones. This would allow grasses and other wild plants grow in order to control soil erosion and encourage pollinators and beneficial insects. Using such measures on land that connects natural areas can go a long way towards conserving biodiversity.

Another approach is to make greater use in agriculture of indigenous species. These are species that tend to be eradicated under modern farm management methods. In West Africa, for example, researchers are helping farmers plant a species of the bush mango tree found in the wild. The time between planting and fruit is only four years (compared to the usual 12 years), making this wild species an attractive candidate for incorporating into existing farming systems.

There may even be situations in which governments decide to pay farmers to carry out environmentally beneficial activities on their land (as is currently practised within the European Union). Such schemes are intended to reward activities that lead to lower but more sustainable productivity, such as creating the wildlife corridors described above. Subsidies might also be used to reward other activities, such as 'resting' intensively farmed land, reducing the use of chemical fertilisers, reducing or halting the use of pesticides, or establishing hedgerows and plantings of native species that attract a range of wildlife.

Of course, an important issue is how developing countries generate funds for farmer subsidies. But if the outcomes are truly beneficial, the practices may ultimately pay for themselves.

Farming with fewer chemicals

Another way to reduce the impact of agriculture on biodiversity is to develop farming techniques that use fewer chemicals. Modern agriculture relies on a high level of chemical input. These include fossil fuels to drive machinery, as well as chemical fertilisers, pesticides and herbicides - all of which affect both soil quality and biodiversity.

The FAO has estimated that a recent doubling of world food production was accompanied by a seven-fold increase in the annual global rate of nitrogen fertilisation and a 3.5-fold increase in phosphorus fertilisation. [5] Yet elevated levels of nitrogen and phosphorus harm biodiversity, as they can encourage a few species - such as the water hyacinth in East Africa's Lake Victoria - to colonise an entire ecosystem.

Strategies to control pests in modern cropping systems have usually been dominated by the use of toxic chemicals. Many pesticides have certainly made a significant contribution to gains in yields. But the indiscriminate and injudicious use of pesticides has led to well-known problems, such as development of resistance by, and subsequent resurgence of, pests. Some of the gains have been eroded as a result. Indeed, overall crop losses due to pests have risen globally, despite increased pesticide use. [6,7]

National and international policies are largely to blame for the increase in chemical inputs. For example, international trade policies that determine quality standards for produce have often encouraged the use of pesticides, as has the availability of pesticide subsidies in many developing countries.

Non-toxic alternative pesticides do exist. These include 'bio-pesticides', whose active ingredients are living organisms such as a bacterium, virus, or plant extract. But their adoption has been hampered by some of the existing regulations. Some registration procedures, for example, only recognise broad-spectrum chemicals.

In developing countries, fertilisers and pesticides are often imported, and therefore place a significant strain on the national purse. These are often used primarily on export crops, and do not improve local food security. Moreover, in developed and developing countries alike, chemical fertilisers and pesticides tend to 'leak' out of farms and, in doing so contaminate the surrounding countryside.

Biodiversity itself can contribute to reducing the use of chemicals in agriculture. Various alternative farming techniques have been developed that seek to do this, such as biological control of pests and weeds.

Stemborer moths, for example - which can destroy up to 80 per cent of maize and sorghum crops - have been controlled in East Africa by planting certain grasses in and around the crops. Invading moths are attracted to chemicals emitted by the grasses, distracting them from the maize. One of the grasses even has its own means of defending itself against the pest, by secreting a sticky substance that traps the insects. [8]

More controversial is the use of genetically modified (GM) crops to reduce the use of chemicals. Such crops have had their genetic make-up modified to make them resistant to herbicides, or enable them to produce their own pesticides.

Most assessments of GM crops in developing countries, however, conclude that for the poorest countries, they are unlikely to make a major impact on the preservation of biodiversity - and certainly not without significant attention being paid to other potentially limiting factors such as soil conditions and water supplies. Furthermore, GM crops could themselves pose a major risk to wild biodiversity. For example, local crop varieties and wild relatives could become 'polluted' with genetic material from GM strains of the same crop.

The real challenge is to develop agricultural technologies - whether new plant varieties, inputs or machinery - that, while using existing ecosystem services to increase production, also reduce the impact of farming procedures on the environment. Nitrogen fixation and mixed cropping, for example, are technologies that can foster thriving soil fauna and crops, and at the same time keep nutrients on the farm without allowing them to pollute waterways.

Reforming national seed policies

Another way of developing forms of agriculture that are more biodiversity-friendly is by reforming national seed policies. The world's range of food crops is already being reduced as a result of industrial-scale agriculture, as is the range of animal varieties. According to the FAO, a third of the 5000 known breeds of farm animals have disappeared in modern times across the world; and a further 30 per cent of those that survive are considered to be at risk. There are several reasons for this disappearance. Industrial farming systems, for example, tend to rely on cultivating large quantities of just a few crops. This provides little incentive to farmers or others to conserve seeds for crops that are no longer in use.

When small-scale agriculture was more prevalent, smallholder farmers took on responsibility for maintaining the diversity of their seed, often out of necessity. These farmers were well aware of the value of conservation to their future livelihoods. In modern agricultural systems, however, this task tends to fall between farmers, the owners of agribusinesses, and national agriculture and environment authorities - with none of these groups being prepared to take full responsibility.

Even in countries that do maintain a strong tradition of small-scale agriculture, however, plant and animal diversity on farms can still be threatened. The danger lies in the national seed policies that govern how farmers select, keep, sell or exchange seeds. In the past, farmers have been able to maintain a diversity of seed stock by freely exchanging seeds with each other. But new international intellectual property regulations being developed by the World Trade Organisation, for example, threaten to undermine, or even prevent, these practices by prohibiting seeds from patented crops from being freely harvested or passed to other farmers. In doing so, the new regulations have ended a practice that has been a mainstay of seed conservation for centuries.

Such trends are not inevitable. The Community Biodiversity Development Conservation programme in the Mekong Delta of Vietnam, for example, illustrates how seed policy can be reworked to openly support informal seed sector development. This project aims to build local capacity to breed, select, produce and supply the seed needed for sustainable agriculture in the Delta.

Many believe that legal frameworks should support a pluralistic variety of seed supply, with farmers served by a number of institutions, including - but not limited to - those in the private sector. But changing legal frameworks requires political will, as well as the willingness to stand up to powerful interests within the global agro-industry that benefit from the current system, and have little inclination to change.

Conclusion

Of all the aspects of biodiversity, the conservation of agricultural biodiversity, and the provision of space for conserving wild biodiversity in agricultural landscapes, has perhaps the greatest potential for practical, sustainable solutions that are implemented because they benefit both people and natural ecosystems.

In recent times, agriculture and biodiversity have coexisted uneasily, with modern agriculture largely winning most battles for resources. Yet the future of each is inextricably bound up in the other.

Only when this lesson has been fully absorbed by policymakers at both national and international levels, and the threats posed by current trends have been fully appreciated, is the necessary action to avoid such threats likely to be implemented. The challenge is a considerable one. But the future of both the world's natural ecosystems, if not of much of humanity's food supply, could be at stake.

Barbara Gemmill is executive director of the Environment Liaison Centre International. Ana Milena Varela is at the International Centre of Insect Physiology and Ecology. Both authors are based in Nairobi, Kenya.
References

[1] Wood, S. et al (2000) Pilot Analysis of Global Ecosystems: Agroecosystems. World Resources Institute.

[2] Pinstrup-Andersen, P. and E. Schioler (2000) Seeds of Contention: World hunger and the global controversy over GM crops. Johns Hopkins University Press.

[3] World Conservation Union (2000) Vision for Water and Nature: a World Strategy for Conservation and Sustainable Management of Water Resources in the 21st Century.

[4] Committee on Sustainable Water Supplies in the Middle East; Israel Academy of Sciences and Humanities; Palestine Academy for Science and Technology; Royal Scientific Society, Jordan; and the US National Academy of Sciences (1999) Water for the Future: The West Bank and Gaza Strip, Israel and Jordan. National Academy Press.

[5] Tilman, D. (1999) Global environmental impacts of agricultural expansion: the need for sustainable and efficient practices. Proceedings of the National Academy of Sciences 96:5995-6000.

[6] Oerke, E. C. et al (1994) Crop Production and Crop Protection: Estimated Losses in Major Food and Cash Crops. Elsevier.

[7] Lewis, W. J. et al (1997) A total system approach to sustainable pest management. Proceedings of the National Academy of Sciences 94:12243-12248.

[8] Khan, Z.R. and A.N. Mengech (2001) Management matters in the war against stem borers. Ecoforum 25(2):46-47.

homepage: homepage: http://www.scidev.net/en/agriculture-and-environment/policy-briefs/modern-agriculture-and-biodiversity-uneasy-neighbo.html